1. Field of the Invention
The present invention relates to a self-dying recombinant strain for measuring contamination of soil or water.
2. Description of the Related Art
A concentration of a contaminant in soil or ground water, a bioavailable concentration, and a concentration of toxicity are different from each other, since a toxicity and a bioavailability of the contaminant is reduced by a process, such as, sorption and the like, performed after the contaminant is released into soil. Therefore, when a toxicity with respect to a receptor is measured, analyzing a toxicity and a bioavailability of a target contaminant may be significantly important.
Various schemes for measuring the toxicity and the bioavailability of the contaminant in soil or groundwater have been developed. Microtox is a toxicity measuring scheme that measures the toxicity of the contaminant based on a degree of inhibition of luminance of a bioluminescent microorganism (Palmer et al., 1998; Sousa et al., 1998). In addition, measuring a biodegradability (Weissenfels et al., 1992; Tang and Alexander, 1999) or a mild extraction (Alexander and Alexander, 2000; Reid et al., 2000) have been widely used. The above mentioned schemes have drawbacks. For example, the schemes may not be compound-specific, the schemes may need to be compared with an organism-based detection scheme, or the schemes may not directly measure the contaminant when the contaminant is in soil. Therefore, the schemes may not take account of interaction between organisms existing in soil or water and the contaminant.
A contaminant detection scheme using a recombinant microorganism has drawn attention since G. Sayler suggested the scheme in the early 1990s. A microorganism is used as a device for specifically and sensitively detecting the contaminant. In most cases, the contaminant detection scheme may be based on a scheme of measuring an amount of luminescence or fluorescence. A promoter of a gene expressed by a target contaminant is combined with a luminescent or fluorescent gene and thus, as an amount of contaminant increases, an amount of luminescence or fluorescence also increases.
When the contaminant contained in soil or water is measured using a recombinant microorganism, the contaminant is extracted from soil, the extracted contaminant is reacted with a recombinant strain, and the reaction is measured. According to the study of Willardson et al. in 1998, BTEX concentrations in soil were measured using a bioreporter Pseudomonas putida mt-2, and a reaction of the bioreporter is measured using soil-ethanol extract to remove the disturbance of soil particles. According to the study of Gu and Chang in 2001, all phenanthrene is extracted using a surfactant, and a toxicity of phenanthrene in soil is measured. However, the above mentioned studies include an extracting process and thus, may not appropriately show the bioavailability and the toxicity of the contaminant.